Support for db persistence. Issue #16

tdt4140-gr1800/app.core/pom.xml

...pp.core/src/main/java/tdt4140/gr1800/app/core/Person.java

...main/java/tdt4140/gr1800/app/db/AbstractDbAccessImpl.java

...e/src/main/java/tdt4140/gr1800/app/db/DbAccessHelper.java

...ore/src/main/java/tdt4140/gr1800/app/db/DbAccessImpl.java

...p.core/src/main/java/tdt4140/gr1800/app/db/IDbAccess.java

...0/app.core/src/main/java/tdt4140/gr1800/app/db/IdMap.java

....core/src/main/resources/tdt4140/gr1800/app/db/schema.sql

...src/test/java/tdt4140/gr1800/app/db/HsqldbAccessTest.java